1. Field of Invention
This invention relates to archery telescopic aiming sights, specifically to an improved method for illuminating such sights for use under poor lighting conditions.
2. Description of Prior Art
A telescopic aiming sight, referred to as a scope, is commonly used in archery to provide a means for more precise aiming by magnifying the target. The optical component of the scope consists of a single lens mounted within a cylindrical barrel. The purpose of the barrel is to serve as a support for the lens and to minimize reflections. The scope is mounted on a sight mechanism which is attached to the bow handle. The bow handle is referred to as the riser. The sight mechanism permits the scope to be raised and lowered with respect to the riser. Lowering the scope has the effect of causing the archer to aim higher, thereby increasing the elevation of the trajectory of the arrow. A higher arrow trajectory is required to hit targets which are located at longer distances. When the bow is drawn, the archer views the target through the scope while also looking through a small pin hole device. The pin hole device is called a peep and is mounted between strands of the bow string. When the bow is drawn, the peep in the bow string is located near the archer's eye, while the scope and sight mechanism mounted on the riser are at approximately arms length. In these positions, the peep and the scope form a simple telescope approximately one meter in length. When used in this manner, the scope provides magnification of the target while the combined scope and peep assembly permit the archer to precisely align the bow with the target. The typical scope also includes a level, liquid filled except for the indicating bubble, to aid in maintaining precise vertical positioning of the bow while aiming. If the bow is unknowingly inclined to one side, the arrow will impact to that side of the aiming point on the target.
The lens of the sight has an aiming mark, usually a circular dot, located at the center of the lens. The archer aims by placing the aiming mark on the bullseye of the magnified target while looking through the small hole in the peep. To obtain the greatest aiming precision, the hole in the peep is typically made very small. Holes as small as one millimeter in diameter are common. While this small diameter improves the archer's ability to aim with high precision, it also significantly reduces the amount of light reaching the archer's eye. Accordingly, under the poor lighting conditions which are often encountered in archery, the aiming mark and level become difficult to see. This inability to clearly see the aiming mark and level have an adverse impact on the archer's ability to aim. Specifically, the aiming process is mentally and physically very challenging, requiring total concentration by the archer. Any distractions tend to break the archer's concentration, reducing shooting accuracy. Difficulties in clearly seeing the aiming mark and level represent a significant distraction. To compensate for the loss of light caused by the small diameter of the peep hole, very bright illumination of the aiming mark and at least some illumination of the level are required.
To provide a brighter aiming mark, U.S. Pat. No. 4,220,983 issued to Schroeder (1980) and U.S. Pat. No. 4,638,565 issued to Podany and Glaseman (1987) both use an illumination method which places the light source itself directly at the center of the lens to serve as a lighted aiming dot. U.S. Pat. No. 5,152,068 issued to Meister (1992) uses a light source which shines on the aiming mark. To provide sufficient brightness, the light source is mounted on a support which protrudes into the viewing area in order to place the light source near enough to the aiming mark to achieve a useable brightness. Another technique in use is to illuminate one end of an optical glass fiber. The other end of the fiber is placed at the center of the lens with the fiber pointed at the archer. The light exiting from the fiber appears as a bright spot visible to the archer. All of these designs have either electrical wires, optical fibers, or other structures crossing the scope viewing area. These structures are objectionable in that they partially obstruct the archer's view of the target through the scope and distract the archer during the aiming process. A further disadvantage is that these structures are near the lens, making cleaning of the lens difficult. In addition, fine wiring and optical fibers on or near the lens surface are easily damaged when attempting to clean the lens.
U.S. Pat. No. 4,977,677 issued to Troescher (1990) disclosed a telescopic archery sight in which one or more light sources are used to introduce light into the edge of the lens. A portion of the light travels internally through the clear lens material and illuminates reticle markings on the lens surface. This approach avoids the problem of extraneous obstructions partially obscuring the scope viewing area. However, only a small amount of the light which is introduced into the edge of the lens actually reaches the aiming mark. The resulting aiming mark brightness is marginal when used with the typical peep having a small hole.